Raid/No Raid

As you may know, RAID, which can be implemented in hardware or software (RHE gives you this option), spreads data a cross multiple disks. Depending on which level you choose, RAID can provide data redundancy to protect the data in the case of hardware failure. Although it can also improve disk performance by increasing read/write speed, RAID uses quite a bit of CPU time, which may be a consideration in some situations.

I suggest you do NOT do not use RAID as a replacement for regular backups. If your system undergoes a catastrophic failure, RAID will be useless. RAID also doesn't take care of something as simple as replacing a file when you delete it by accident. In these cases, a backup on a removable medium (that has been removed) is the only way you will be able to restore a file system. Good luck!

 

I don't they were planning on replacing backups with raid, rather storing backups on a raid array made up of three disks, which is fine.

If one drive fails, you can still rebuild your backups. Depending on how raid is implemented (hardware/software) you may or may not see a general system slowdown while the array is rebuilt.

I prefer running raid 1 (mirroring) as opposed to raid 5 (striping) because there it's easier to rebuild from... a dead drive doesn't affect performance immediately, so I can schedule a rebuild for the off-hours.

 

RAID1 wont be a hit on performance at all. But I wouldn't suggest software raid1. Performance (in my tests) is the exact same, but in the case of power loss RAID1 (software) has a good chance of being destroyed. And I mean GOOD chance. Had it happen 3 times

 

CMIIW, but software RAID of any type can have issues during a power loss... so can hardware RAID for that matter...

Power loss isn't fun, regardless of what system you're using

 

Has anyone here truly gone through a catastrophic failure of one drive on a RAID 1 running Cpanel and recovered cleanly from it ?.

I know how it's supposed to work, but what did you experience, what did it look like, what steps did you take to recover and how long did it take?.

We backup the hell out of our servers and keep multiple copies on both mounted drives as well as rync'd .TAR files of paritiions AND also swap our backup drives monthly to have even more redundancy, but the RAID thing sounds like a painless recovery from a dead drive, but it would be nice to hear a real world experience from a web host running cpanel.

 

If you mean having a drive fail on a system set up with raid1, yes, twice last week. Both servers brand new, w/ new drives, hot swap enabled. A western digital 500gb and seagate 320gb. Recovering from it didn't require powering down, just pulling the old one and sliding in a new one and watching 3ware detect it and rebuild it with no intervention whatsoever.

Can't complain about the seagates, but almost can. So far 3 out of a batch of 24 new drives failed in the first month. Western digital 1 out of 2. Hitach 0 out of 4. The western digitals were more of a test to verify that they still suck, and they passed the test.

 

Do you suppose that's a good review: that they met your expectations? :p